National Centre for Radio Astrophysics TATA INSTITUTE OF FUNDAMENTAL RESEARCH NCRA, POST BAG 3, GANESHKHIND, PUNE UNIVERSITY CAMPUS, PUNE 411007, Tel : 91 (20) 2571 9000, 2571 9111 ; Fax : 91 (20) 2569 7257

Announcement of Opportunity: Cycle 39

(October 2020 – March 2021) Observations with the Giant Metrewave Radio Telescope (GMRT) Khodad, India

Proposal Deadline : Friday, July 31, 2020, 17:00 IST

The National Centre for Radio Astrophysics (NCRA) invites proposals for observations with the GMRT for Observation Cycle 39 (October 2020 to March 2021). The deadline for receiving these proposals is 17:00 IST (UTC+5.5 hrs), Friday, July 31, 2020 (this is 2 weeks later than the normal deadline, to mitigate constraints and delays due to the Covid-19 pandemic). The proposals will be reviewed and evaluated by the GMRT Time Allocation Committee (GTAC), which will make recommendations for allocation of observing time for each proposal.

Status of the GMRT : Over the last few years, the GMRT has been going through a major upgrade which was completed in March 2019. Cycle 39 will have the upgraded GMRT (uGMRT) available for observations with the full array of 30 antennas for all the 4 bands of the uGMRT: 120-240 MHz (Band-2), 250-500 MHz (Band-3), 550-850 MHz (Band-4) and 1000-1460 MHz (Band-5), in regular release mode. All the uGMRT observations will be with a 30- antenna back-end with a choice of 100, 200 or 400 MHz processing bandwidth for the correlator (alongwith a zoom mode for spectral line observations), with the default choice of 2048 channels, as well as the corresponding IA/PA beamformer outputs for pulsar observations. However, some new and advanced modes will only be available on a shared risk basis, meaning that (a) these new features and modes may not be fully tested and guaranteed for performing as per the specs, and the user shares the risk of failure and/or under performance of these modes of the system, and should be ready to use these on an "as is, where is" basis for their observations; (b) as a corollary of the above, no make-up time will be allotted for under-performance of the system in these modes.

Current technical details about the legacy and upgraded GMRT, available frequency bands and usable bandwidths, system parameters, modes in regular release and shared risk categories, and expected performance information can be found in the updated GMRT Specifications and Status document at http://www.ncra.tifr.res.in/ncra/gmrt/gtac.

Observing slots and configurations : Science observations will be scheduled round the clock except for Wednesday 09:00 hours to Thursday 18:00 hours (each week) as this slot is reserved for maintenance and test activities. The distribution of the observing slots over the duration of Cycle 39 is shown in the dummy schedule at http://www.ncra.tifr.res.in/ncra/gmrt/gtac. As can be noted, there are fewer time slots available for scheduling in the LST range of 16 to 24 hrs, and we request users to bear this in mind when preparing their observing proposals. The observatory will strive to maintain the target of 26 working antennas for every GTAC approved observation. Some of the existing observing modes of the legacy system and flexibility of observing settings may be partially affected by the changes due to the upgrade.

Proposals can use only the GMRT Wideband Backend (GWB) (that serves the upgraded GMRT) as the primary back- end. The choice of having legacy GMRT Software Backend (GSB) as the primary backend does not exist. Proposers who wish to use only the GSB can do by specifying it as the secondary backend in the designated text box. However such GSB-only proposals would still have to give the specifications for the default GWB setup. Also, the control and monitor system will be upgraded to new Tango based GMRT Control (TGC) system due to which the structure and syntax of the observing files will be somewhat different from the legacy GMRT Online system.

Proposal submission and processing : Proposals are to be submitted online via the NCRA Archive and Proposal Management System (NAPS), available at https://naps.ncra.tifr.res.in, which provides password authenticated, web browser based interface for proposal submission. Note that the proposals may be submitted only by the PIs, but all co- Is also need to be registered users of the system. All PIs and co-Is since Cycle 15 are registered users. Proposers are required to submit 2 additional documents alongwith the usual scientific justification document : a technical justification document, and the output from the GMRT Exposure Time Calculator (ETC), which can be found at http://www.ncra.tifr.res.in/etc. For any unresolvable problems with the NAPS interface, please contact the help desk at [email protected] .

Proposals will be processed by the GTAC with external refereeing as needed and the proposers intimated of the time allocation. The GTAC may seek inputs from the GMRT Observatory on matters relating to the technical justification of the proposals. Proposals requiring more than 100 hours of observing time will be treated as “large proposals”. They will be reviewed in a manner appropriate for each one of them and, if necessary, the time allocation will be split over several cycles. Target of Opportunity (ToO) proposals can also be submitted for the regular cycle, which will be reviewed by the GTAC in the usual manner, but any time allotted will be scheduled dynamically, as and when the specified trigger conditions are met. The exact procedure for triggering a ToO observations will be informed to the PIs. ToO proposals with significant overlap of science goals and trigger criteria may be asked to share the data. The total time allotted for such GTAC ToO proposals will not be more than 5% of the total GTAC time allocation for the cycle. The policy document for GTAC ToO proposals can be found at http://www.ncra.tifr.res.in/ncra/gmrt/gtac.

In addition to regular GTAC proposals, users can also avail of Director’s Discretionary Time (DDT) facility, as relevant. DDT time is meant for special uses, such as (i) pilot observations / feasibility studies which might lead to future GTAC proposals; (ii) urgent confirmatory observations; (iii) ToO observations, primarily intended for short-lived or time- dependent astronomical phenomena. DDT time allocations are subject to availability of time and convincing scientific goals, and are cleared by the Centre Director, NCRA. Requests for these should also be submitted via NAPS, using the option for DDT proposals. DDT proposals can be submitted at any time of the year.

Scheduling and observing : After a proposal has been allotted time and scheduled, queries related to the observing schedule should be sent to [email protected] . For other aspects of the observations, please write to [email protected] . Queries regarding travel logistics can be addressed to Secretary for Operations at secr- [email protected] . DDT and ToO observations will be scheduled in the empty “white” slots in the GMRT schedule, without affecting the scheduled GTAC observations, as far as possible. The GMRT supports absentee observing for the standard interferometric and beamformer modes with the existing legacy system, as well as with the regular, full release interferometric and beamformer modes of the uGMRT system. Users who would like to avail of this facility should prepare and send their set up configuration, command files and source list at least 10 days before their observations to [email protected] . A set of tools available to users for help with their observations can be found at http://www.gmrt.ncra.tifr.res.in/~astrosupp . There is a possibility of downtime due to power outages, wind (particularly during May-August), ionospheric activity, RFI etc. There is some scope for make up for time lost due to such reasons. In case of such requirements, users should send an email requesting compensatory telescope time, giving details of the problems, to [email protected] . Post observations, the interferometric data will be made available for download from NAPS, after an interval of one day. NCRA continues to encourage first time users to be present for observations and spend a few days of extra time to become familiar with the recommended observing/editing/calibration procedures.

Data Release : Data from all standard observations with the GMRT will be made public 18 months after the date of observation. For all ToO / DDT observations, the corresponding period is 3 months. The status and details of all the observations since 2002 can be obtained from https://naps.ncra.tifr.res.in/goa .

Centre Director NCRA-TIFR